The invention relates generally to welding systems, and more particularly to improved grounding connections for pipe welding and other welding applications.
An essential part of welding practice is properly grounding the workpiece. This ensures that the workpiece is at or very near the same potential as a ground terminal of a power supply so that a circuit can be completed through the workpiece to establish and maintain a welding arc. Consequently, a primary source of compromised welds is faulty ground connection to the workpiece. Traditionally, grounding is done through a work clamp that clamps onto the workpiece (or a fixture to which the workpiece is mounted) and which is grounded through a cable extending back to a welding power supply. However, work clamps are only suitable for workpieces of limited size and shape, such as those with straight or flat sides and of manageable size. However, using work clamps is unfeasible for pipe welding, or for other unwieldy shapes due to limited contact areas (e.g., where two joints of pipe are closely positioned end-to-end). Unfortunately, commonly used grounding techniques for pipe welding are to insert a grounding device into the gap between the two pipe joints or to place a grounding device on top of the two pipe joints, often being secured only through gravity. These grounding devices may just be pieces or blocks of conductive material, most of which are not specifically designed for the function of creating a good ground connection. The existing grounding techniques establish fragile contact angles that only touch a small surface of the workpiece. These weak connections result in a higher level of resistance as current is restricted, which can weaken the integrity of the weld and cause defects.
Additionally, the existing grounding techniques do not include a convenient means of measuring critical parameters such as current, voltage, and resistance, which can be used to verify an acceptable connection. This is an important function because the point of grounding contact on the workpiece may not always provide a sufficiently conductive surface. It is not uncommon for the workpiece to be corroded or soiled at the point of contact with the ground connection, preventing a solid ground connection. For example, there may be rust or other nonconductive debris between the conductive material of the workpiece and the grounding device. The result is a faulty or high resistance ground connection, potentially compromising the quality of the weld. Without a means of measuring and indicating ground connection quality, the operator has no knowledge of the poor connection and therefore may continue to weld with a faulty ground connection. A lack of feedback makes it difficult or impossible to detect and correct a poor ground connection. This is especially problematic in advanced process equipment as the current flow is precisely controlled to achieve optimal results.
There is a need for an improved grounding device that is capable of establishing a robust grounding connection as well as a means to verify that connection.